One focus of the current debate is whether or not sexual selection includes intrasexual competition for breeding opportunities instead of simply competition for mates (Clutton-Brock 2007, 2009, 2010; Roughgarden and Akçay 2010).
Shuker’s definition includes competition for resources that influence the quantity or quality of mates obtained (Lebas 2006; Stockley and Bro-Jørgensen 2011), but it excludes resource competition that only affects survival or fecundity, as this latter category does not differentiate sexual selection from fecundity or mortality selection (Wade and Arnold 1980; Endler 1986; Andersson 1994).
These patterns reveal a key sex difference in sexual selection: Although females may compete for the number of mates, they appear to compete more so for access to high-quality mates that provide direct and indirect (genetic) benefits.
As is the case in males, intrasexual selection in females also includes competition for essential resources required for access to mates.
2006; Clutton-Brock 2009, 2010; Roughgarden and Akçay 2010; Shuker 2010).
The first point concerns the contrast between competition for mates and competition for resources.
When females exhibit versions of these traits, their evolutionary significance has proven to be enigmatic.
Are these traits nonfunctional by-products of a genetic correlation with males (Lande 1980)?
Or do females use these exaggerated traits and behaviors to compete for mates in a context similar to sexually selected male–male competition?If mate quality affects the magnitude of mating success, then restricting sexual selection to competition for quantity of mates may ignore important components of fitness in females and underestimate the role of sexual selection in shaping female phenotype.In the future, understanding sex differences in sexual selection will require further exploration of the extent of mutual intrasexual competition and the incorporation of quality of mating success into the study of sexual selection in both sexes.In recent years, behavioral ecologists have shown increased interest in sexual selection in females (Heinsohn et al.2005; Lebas 2006; Clutton-Brock 2007, 2009; Watson and Simmons 2010), focusing especially on the phenotypic variation in and functional significance of female ornamentation (Amundsen 2000; Amundsen and Parn 2006; Kraaijeveld et al.